SXT

Soft X-Ray TelescopeOnboard theYohkoh Satellitehttp://solar.physics.montana.edu/winter/RSS_Presentation/SXT.ppt

Overview

Brief DescriptionThe Trouble with X-RaysOptical DesignSystem ParametersBlock DiagramEffective AreasWhy I Don’t Have a SNR Calculation NOBODY HAS A SNR CALCULATION !!!

Sample dataReferences

Soft X-Ray Telescope (SXT) was designed to study “thermal” X-ray emissions from solar coronal sources (1/2 MK-30 MK) 0.25 – 4 keV range (3-45 Å)

E[keV]=12.40[keV* Å]/[Å] Passive sensor

One of many instruments onboard Yohkoh Satellite

Launched from Kagoshima, Japan on August 31, 1991 Trae Winter arrives in Bozeman on January 6, 2002 to take

over MSU SXT science planning January 9, 2002 announced (to me at least) that Yohkoh was

lost on December 14, 2001.

Brief Description I

Brief Description II: SXT

http://isass1.solar.isas.ac.jp/yohkoh/images/teemsxt.gif

Brief Description III: Yohkoh (Solar-A)

Ogawara, Y., et al. 1991

Atmospheric transmission of X-Ray and E.U.V. is essentially 0 Sounding Rockets Satellites

X-Rays ignore “most” refractive optics The index of refraction, n[], is ~1 at X-ray

wavelengths for all material

X-Rays are not easily reflected More likely to be transmitted or absorbed

The Trouble withX-Rays I

X-Rays can be made to reflect off of high density materials at shallow angles Analogous to total internal reflection

critical is the angle in arcminutes, is the mass density in g cm-3, E is the photon energy in keV http://harris.roe.ac.uk/~jcm/thesis/thesis.html

The Trouble withX-Rays II

69.4critical E

Optical Design I:Wolter I Telescope

http://www.sr.bham.ac.uk/xmm/images/mirrors/lightanim.gif

Optical Design II:“Ray-Trace” of SXT (Mod. Wolter I)

http://www.lmsal.com/SXT/

Optical Design III:Breakaway

http://www.lmsal.com/SXT/

System ParametersCCD Cooled to ~-18°C Array Size:

1024 X 1024Pixel Size:18.281 0.002 m 2.4528 0.0005” 1779 km

Time Resolution:0.5 sec. (Special)2.0 sec. (normal)

TelescopeGeometrical Area261.75 mm2

Effective Area (Peak) 78 mm2 @ 8 ÅEffective Focal Length 1535.6 mm

ConstructionZerodur™ Glass/Ceramic420 Å Au on 80 Å CrSurface Roughness3.8 Å r.m.s.

Block DiagramMirror

FilterFilter CCD

Shutter

Data

Processor

Memory

10 MBGoldstone

Canberra

Madrid

Kagoshima

Effective Area I

Effective Area II:Now with filters

a) No filter

b)1265 Å Al

c) Dag

d)2.52 m Mg

e) 11.6 m Al

f) 119 m Be

SNR Calculation I

X

Energy Per [Å] CCD Response (e-/keV)

Sum the electons/s DN=(#E/100)+(13,30,69)

For noise repeat but the photon spectrum is now the square root of itself.

SNR Calculation IAssumptions

Solar active region

Electron Density 1 x 109 particles cm-

3

A certain set of elemental abundances

Ionization equilibrium approximations

SNR = 1.73 or 2.4 dB

Signal=22.5 DN s-1 pixel-1, Noise= 13 DN s-1 pixel-1

Why don’t I still have a true SNR??

Sample Data

Sample Data

http://www.lmsal.com/ypop/sxt_movie.html

ReferencesOgawara, Y., et al. 1991, “The Solar-A Mission - an Overview”, SOLAR PHYSICS, 136, pp. 1-16

Tsuneta, S., et al. 1991, “The Soft X-ray Telescope for the SOLAR-A Mission”, Solar Physics, 136, pp. 37-67

Web Resources:

Yohkoh Data Analysis Guide and Instrument Guide Available at

http://umbra.gsfc.nasa.gov/yohkoh_archive.html#YAG

ISAS Yohkoh Web Page

http://isass1.solar.isas.ac.jp/yohkoh/images/

James Manners’ Thesis Page

http://harris.roe.ac.uk/~jcm/thesis/thesis.html

Lockheed Martin Solar & Astrophysical Lab Yohkoh Web Page

http://www.lmsal.com/SXT/

Marshall Space Flight Center

http://science.nasa.gov/ssl/pad/solar/

Yohkoh Public Outreach Project

http://solar.physics.montana.edu/YPOP/

Slides that I deleted due to lack of time

Scientific Context:Begin the Space Age

“Almost” no E.U.V. or X-Ray photons @ surfaceNo reason to expect solar X-RaysSounding rockets detected X-RaysThen came OSO, SkylabRESOLUTION!!!

http://science.nasa.gov/ssl/pad/solar/images/s054_1.gifhttp://science.nasa.gov/ssl/pad/solar/images/skylab2.jpg

Temperature ResponseBased on synthetic spectra with certain input

parameters (elemental abundances, electron density, emission measure (amount of emitting plasma))